The present invention relates to an installation for preparing dampening solutions for offset printing with a device for preparing a dampening solution and a device for feeding one or more basic liquid materials for preparing the dampening solution into the device for preparing the dampening solution.
In offset printing, it is necessary to wet the surface of the offset printing plate with a dampening solution, which prevents acceptance of printing ink by the non-printing places of the offset printing plate. It is generally customary to cycle the dampening solution between the printing press and a device for preparing dampening solution, in which the dampening solution is formulated from different basic materials. In this way, the dampening solution, consumed in the printing process, can be replaced continuously by fresh dampening solution.
Such systems for preparing and supplying dampening solutions are generally known, for example, from the European patent application 02 004 480 of the Applicant. The known equipment comprises cooling devices, which ensure that the prepared dampening solution, supplied to the printing press, has a suitable process temperature, so that the alcohol, contained in the dampening solution, does not evaporate and the flowing and wetting behaviors are optimized. For wet offset printing, a dampening solution temperature ranging from 8° to 12° C. is typical and must be adhered to with a tolerance not exceeding ±1° C. Fluctuations in the temperature of the dampening solution, supplied to the printing rollers, lead to a change in the quality of the printing result. It is therefore appropriate that the cooling system in the dampening solution cycle comprises a control segment, which, on the basis of an actually measured temperature of the dampening solution, controls the temperature of the dampening agent, supplied to the printing rollers, at a nominal value.
If new basic materials, the temperature of which differs appreciably from the temperature existing in the cycling dampening solution, are fed into the device for preparing dampening solution for the purpose of preparing fresh dampening solution, it may happen that the device for cooling the dampening solution cannot eliminate this difference because of the reaction time required by the control segment, so that the temperature of the dampening solution is subjected to fluctuations. In such a case, the temperature may leave the specified tolerance range, so that problems arise in the printing process.